Amino nitriles as metal complexing



AMINO NITRILES AS METAL COMPLEXING AGENTS IN CRACKED GASOLINE Donald J. Shields, John W. Thompson, and M B Knowles,

Kingsport, Tenm, assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application March 28, 1952, Serial No. 279,215

6 Claims. (Cl. 44-72) This invention relates to a method of improving the quality of petroleum hydrocarbons, and more particularly, to improving the quality of petroleum hydrocarbons which have been treated with heavy metal salts, such as mercury salts, copper-containing reagents, etc., for the removal or conversion of sulfur compounds.

It is well known to remove sulfur compounds, such as mercaptans, from petroleum hydrocarbons, such as gasoline motor fuels, or to convert such mercaptans into less objectionable compounds by appropriate chemical treatment, generally referred to as a sweetening operation. One quite common method of sweetening involves the use of a doctor solution made from sodium hydroxide and lead oxide. Treatment of the sour gasoline with this solution and added sulfur converts the mercaptans to alkyl disulfides. The amount of sulfur used must be very carefully controlled since excess sulfur in the gasoline is harmful with respect to corrosiveness, lead susceptibility, and inhibitor susceptibility. On the other hand, the use of insuificient sulfur causes lead mercaptides to be left in the fuel.

Instead of using the doctor solution method, it has been previously proposed to substitute other sweetening operations employing copper salts for the purpose of removing the sulfur compounds or converting them into less objectionable substances. This operation is widely used for the treatment of petroleum motor fuels, such as gasoline. Frequently, in the copper sweetening process, various copper compounds may be carried over into the treated gasoline where they are very objectionable, since even in trace concentrations they catalyze oxidative deterioration of the treated hydrocarbon. This dif- Qiculty is somewhat alleviated through the use of the known antioxidants, although the amount of improvement is not great enough to completely overcome the objections noted above. It is, therefore, desirable to provide some method which would substantially completely remove, or render harmless, all heavy metal compounds from the petroleum hydrocarbon, thus allowing the antioxidant to function at its fullest efficiency.

It is, therefore, an object of our invention to provide an improved method of rendering harmless heavy metal salts, such as those of copper, in petroleum hydrocarbons. Another object is to render petroleum hydrocarbons, such as cracked gasoline, more stable to oxidative deterioriation catalyzed by metals and to permit more effective use of gasoline antioxidants.

Still another object is to provide a new class of effective treating agents for petroleum hydrocarbons, such as cracked gasoline. Other objects will become apparent from a consideration of the following description and examples.

According to our invention, we provide the novel efnited States Patent fects mentioned above by treating a petroleum hydrocarbon containing heavy metal salts, such as those of copper, with an amino nitrile. The amino nitriles useful in practicing our invention comprise those represented by the following general formulas:

wherein R, R1, R2, R3, R4, R5, R7, R8 and R9 each represents a hydrogen atom, an alkyl group (e. g. methyl, ethyl, etc.), or an aryl group (e. g. phenyl, o-, 111-, and p-tolyl, etc.), Rs represents a hydrocarbon aryl group (e. g. phenyl, 0-, m-, and p-tolyl, etc.), X represents an alkylene group or an arylene group, d represents a positive integer of from 1 to 3, and n represents a positive integer of from 1 to 2. Amino nitriles containing only carbon, hydrogen and nitrogen atoms have been found to be especially useful in practicing our invention. Typical amino nitriles included within the scope of Formulas I, II and III above comprise the following:

1. Hydrazodiisobutyronitrile CH: (3H3 C Ila-4 -NH-NH-C C H;

N N 2. a,af-Ethylenediamino-bis (propionitrile) CH;CHNH-CH:CHNHGH-CH3 ON N . a,u'-Ethylenediamino-bis (isobutyronitrile) $113 CH3 CHz-C-NH-CHzCHq-NH- OH3 N ON 4. a,a-Ethylenediamino-bis (phenylacetonitrile) H OsH NHCHzCHz-NHCeH N ON 5. a,a'-Triethylenetetramino-bis (isobutyronitrile) CH on, o m-d NH-C Hie Hz-NH-O 112C Hz-NH-O H20 nrNH-b-o H,

6. a,m'-Triethylenetetramino-bis a-phenylpropionitrile CH3 CH3 0 fins-( 3 -NHO HQC H NH-C Hi0 Hz-NH-C 11,0 Hz-NH-(l-C 0151 N nn 7. a-Anilinoisobutyronitrile 8. a,a-p-Phenylenediamino-bis (isobutyronitrile) The amount of amino nitrile used according to our invention can be varied depending upon the particular petroleum hydrocarbon which is being stabilized. Generally, on the order of from 0.0001 to 0.1 weight percent of the amino nitrile is adequate for the purposes of our invention. The exact concentration of amino nitrile will, of course, depend somewhat on the concentration of heavy metal salt which remains after the sweetening operation. The amino nitrile deactivator can be added to the petroleum hydrocarbon in its natural state, or it can be added in the form of a concentrated solution in some organic solvent, such 'as methanol, benzene, 1,4- dioxane, etc.

The petroleum hydrocarbon containing the deactivator can be further stabilized by the addition of conventional antioxidants, such as p-aminophenols, hydroquinone, butylated hydroquinone, butylated hydroxyanisole, pphenylenediamines, etc.

The efliciency of the amino nitrile deactivators of our invention was determined by means of oxygen bomb stability tests on treated and untreated samples of coppercontaining cracked gasoline. In some instances, the gasoline contained one of the conventional antioxidants, which was conveniently added just prior to testing. Simultaneously, control tests were made on gasoline containing various combinations of copper and antioxidant, no deactivator being added. In the examples described below, the copper was added in the form of a benzene solution of copper oleate and the antioxidant used wa N-n-butylp-aminophenol. The oxygen bomb stability test described above paralleled that described in Industrial and Engineering Chemistry, volume 24 (1932), page 1375. The induction period was measured as the times in minutes before rapid oxidation of the gasoline began, as evidenced by a sharp drop in oxygen pressure. The following examples will serve to illustrate more fully the manner whereby we practice our invention.

Example 1.--A Pennsylvania cracked gasoline having a blank induction period of 45 minutes, which was raised to 445 minutes upon addition of 0.0048 weight percent of the gasoline antioxidant, N-n-butyl-p-aminophenol, was treated with a benzene solution of copper oleate sufiicient to introduce 1.0 mg. of copper per liter. This treatment reduced the induction period to 165' minutes, thus showing the harmful effect of copper upon gasoline stability even in the presence of an eflicient antioxidant. However, the addition of 0.0010 weight percent of a-anilinobutyronitrile to this inhibited copper-containing gasoline gave an induction period of 362 minutes, thus indicating considerable restoration of the induction period lost because of the presence of the copper.

Example 2.-The same inhibited (i. e. containing N-nbutyl-p-aminophenol), copper-containing gasoline described in Example 1 was treated with 0.0010 weight percent of a,a'-triethylenetetramino-bis (isobutyronitrile) raising the induction period to 330 minutes.

Example 3.The same inhibited, copper-containin g gasoline described in Example 1 above was treated with 0.0010 weight percent of hydrazodiisobutyronitrile raising the induction period to 300 minutes.

In a like manner, a number of other compounds falling within Formulas I, II and III above were tested as copper I deactivators, and the results obtained, along with those TABLE Eflectiveness of aminonitriles as copper deactivators for gasoline BA Deactivator g wt" p, as: Percent Y Wt. Period ame Percent 0 None 0 45 0 ..do.. 0 445 1.0 do 0 l. 0 Hydrazodiisobutyronitrile. 0. 0010 300 1. 0 a,a'-Ethylenediamino-bis 0. 0010 255 (propioru'trile) -1. 0 u,a-Ethylenediamino-bis 0. 0010 345 (lsobutyronitrile) 1. 0 a,zx'-Ethylenedlamino-bis 0. 0010 335 (phenylacetonltrile). 1.0 a,a-Trlethylenetetra- 0.0010 330 mino-b1s(is0butyronitrile). 9 0.0048 1.0 a,a-Triethylenctetra- 0.0010 265 miI10-biS(a-I)h enylpropionltrlle) 10 0. 0048 1. 0 a-Anilinolsobutyronitrilc. 0. 0010 302 11 0.0048 1.0 a,a-p-Phenylencdin- 0.0010 375 rhino-bis (lsobutyronitrlle) The amino n1tr1les represented by Formulas I, II and III above can be prepared by condensing a monoamine or polyamine with an aldehyde or ketone in the presence of hydrocyanic acid according to the process described in Ulrich et al. U. S. Patent 2,205,995, issued June 25, 1940. Typical amines which can be used in the process of Ulrich et a1. comprise hydrazine, ethylene diamine, diethylenetriamine, triethylenetetramine, N,N'-dimethylethylenediamine, N,N-diethylethylenediamine, p-phenylenediamine, aniline, etc. Typical aldehydes or ketones which can be used comprise formaldehyde, acetaldehyde, propionaldehyde, isobutryoaldehyde, phenylacetaldehyde, acetone, methylethyl ketone, etc. The hydrocyanic acid used in the condensation is generally formed in situ as described in Ulrich U. S. Patent 2,205,995.

What we claim and desire secured by Letters Patent of the United States is:

1. A cracked gasoline, which has been treated with a copper-containing reagent, containing from 0.0001 to 0.1 weight percent, based on the cracked gasoline, of an amino nitrile selected from the group consisting of those represented by the following general formulas:

11 wherein R, R1, R2, R3, R4, R5, R7, Ra, and R9 each represents a member selected from the group consisting of. a hydrogen atom, a lower alkyl group, and a monocyclic aryl group, R6 represents a monocyclic hydrocarbon aryl group, X represents a member selected from the group consisting of an alkylene group and a phenylene group, d represents a positive integer of from 1 to 3, and n represents a positive integer of from 1 to 2.

2. A cracked gasoline, which has been sweetened with a copper-containing reagent, containing from 0.0001 to 0.1 weight percent, based on the weight of the petroleum hydrocarbon, of a,a'-p-phenylenediamino-bis(isobutyronitrile).

3. A cracked gasoline, which has been sweetened with a--copper-containing.reagent, containing from 0.0001 to 0.1 weight percent, based on the weight of the petroleum hydrocarbon, of a,a'-ethylenediamino-bis (isobutyronitrile).

4. A cracked gasoline, which has been sweetened with a copper-containing reagent, containing from 0.0001 to 0.1 weight percent, based on the weight of the petroleum hydrocarbon, of a,u'-ethylenediamino-bis (phenylacetonitrile).

5. A cracked gasoline, which has been sweetened with a copper-containing reagent, containing from 0.0001 to 0.1 weight percent, based on the weight of the petroleum hydrocarbon, of a,a-triethylenetetramino-bis (isobutyronitrile).

References Cited in the file of this patent UNITED STATES PATENTS Guillaudeu Feb. 16, 1932 Lewis Dec. 6, 1938 

1. A CRACKED GASOLINE, WHICH HAS BEEN TREATED WITH A COPPER-CONTAINING REAGENT, CONTAINING FROM 0.0001 TO 0.1 WEIGHT PERCENT, BASED ON THE CRACKED GASOLINE, OF AN AMINO NITRILE SELECTED FROM THE GROUP CONSISTING OF THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULAS: 